docs: def _compute_magnitude_term(self, C, mag):
          """
          Returns the magnitude scaling factor (equation (2), page 144)
          """
          fmag = C['c0'] + C['c1'] * mag
          if mag <= 5.5:
              return fmag
          elif mag > 6.5:
              return fmag + (C['c2'] * (mag - 5.5)) + (C['c3'] * (mag - 6.5))
          else:
              return fmag + (C['c2'] * (mag - 5.5))